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Suppression of CFTR-mediated Cl(-) secretion by enhanced expression of epithelial Na(+) channels in mouse endometrial epithelium.

The present study investigated the effect of enhanced expression of epithelial Na(+) channels (ENaC) on the cystic fibrosis transmembrane conductance regulator (CFTR)-mediated Cl(-) secretion in the mouse endometrium using the short-circuit current technique. The amiloride sensitivity of the basal current of the cultured endometrial epithelia was found to vary with the magnitude of the basal current, the higher the basal current the greater its sensitivity to amiloride, indicating possible elevation of ENaC expression. However, the magnitude of the forskolin-induced Isc, previously demonstrated to be mediated by CFTR, decreased as the amiloride sensitivity of the basal current increased, suggesting a possible inhibitory effect of elevated expression of ENaC on CFTR-mediated Cl(-) secretion. The Matrigel concentration for culturing the endometrial epithelia was found to affect the amiloride sensitivity of the basal current as well as the forskolin-induced Isc in opposite directions. However, competitive RT-PCR demonstrated that the expression of both ENaC and CFTR was enhanced in Matrigel-treated culture, suggesting that the reduced forskolin-induced Isc with enhanced amiloride sensitivity was not due to a reduction in CFTR expression, but rather suppression of CFTR function by enhanced ENaC expression. In addition to the previously demonstrated inhibition of ENaC by activation of CFTR, the present results reveal possible regulation of CFTR by ENaC. The interaction between the two may be one of the underlying mechanisms for balancing Na(+) absorption and Cl(-) secretion across epithelia.

Animals↗

Intracellular FGF-2 promotes differentiation in T-47D breast cancer cells.

To test the implicated role of basic fibroblast growth factor (bFGF; FGF-2) in promoting differentiation in breast cancer, we enforced the expression of FGF-2 in T-47D breast cancer cells. Expression of FGF-2 conferred an overall less malignant phenotype to T-47D cells as revealed by their reduced proliferative response, impaired capacity for anchorage-independent growth, and invasion through Matrigel. To understand one candidate mechanism for the intracellular FGF-2-mediated anti-invasive effect, we examined the effect of FGF-2 on T-47D cell motility. Addition of recombinant FGF-2 to the growth medium markedly enhanced cell motility while constitutive expression of intracellular FGF-2 significantly inhibited the migratory potential of T-47D cells in a dominant manner. FGF-2-expressing T-47D cells also formed relatively defined branching structures in Matrigel matrices, a characteristic phenotype of differentiation in breast cancer cells. These data suggest a potential role for FGF-2 in promoting functional differentiation of breast epithelial cells.

3T3 Cells↗

HARP induces angiogenesis in vivo and in vitro: implication of N or C terminal peptides.

HARP (heparin affin regulatory peptide) is a growth factor displaying high affinity for heparin. In the present work, we studied the ability of human recombinant HARP as well as its two terminal peptides (HARP residues 1-21 and residues 121-139) to promote angiogenesis. HARP stimulates endothelial cell tube formation on matrigel, collagen and fibrin gels, stimulates endothelial cell migration and induces angiogenesis in the in vivo chicken embryo chorioallantoic membrane assay. The two HARP peptides seem to be involved in most of the angiogenic effects of HARP. They both stimulate in vivo angiogenesis and in vitro endothelial cell migration and tube formation on matrigel. We conclude that HARP has an angiogenic activity when applied exogenously in several in vitro and in vivo models of angiogenesis and its NH(2) and COOH termini seem to play an important role.

Amino Acid Sequence↗

Metal-catalyzed oxidation of extracellular matrix proteins promotes human mesangial cell apoptosis and is associated with enhanced expression of Bax and caspase activation.

Oxidative injury in glomerular disease may oxidize extracellular matrix proteins which might modulate their interaction with mesangial cells and thereby account for the hypocellularity seen in advanced glomerulosclerosis. In this study we evaluated whether oxidation of extracellular matrix could modulate human mesangial cell apoptosis. Human mesangial cells were seeded onto plates coated with unmodified (control) or oxidized Matrigel, laminin, or type IV collagen. Mesangial cell apoptosis was increased on oxidized Matrigel as well as on oxidized laminin and type IV collagen. Mesangial cells behaved similarly on plates coated with control and oxidized forms of the integrin ligand-containing peptide GRGDSP. Cells on oxidized matrix demonstrated enhanced expression of Bax, increased fragmentation of PARP, and diminished apoptosis in the presence of the interleukin-1 beta converting enzyme inhibitor Ac-Tyr-Val-Ala-Asp-aldehyde. These data suggest that oxidation of extracellular matrix proteins may enhance human mesangial cell apoptosis via a mechanism that appears to involve enhanced expression of Bax and caspase activation. This may account for irreversible mesangial hypocellularity in glomerulosclerosis.

Apoptosis↗

Suppression of ATP-induced Cl(-)secretion by enhanced expression of epithelial Na(+)channels in mouse endometrial epithelium.

We have studied the effect of enhanced expression of epithelial Na(+)channels (ENaC) on the ATP-induced Cl(-)secretion in the mouse epithelium using short-circuit current (I(SC)) and RT-PCR techniques. The amiloride sensitivity of basal current (I(b)) across the cultured endometrial epithelia was found to vary with the magnitude of the I(b), the higher the I(b)the greater its sensitivity to amiloride, indicating possible elevation of ENaC. However, the magnitude of ATP-induced I(SC), previously demonstrated to be mediated by Ca(2+)-activated chloride channel (CaCC), decreased as the amiloride sensitivity of the I(b)increased, suggesting a possible inhibitory effect of elevated expression of ENaC on ATP-mediated chloride secretion. The Matrigel treatment for culturing the endometrial epithelia affected the amiloride sensitivity of the I(b)as well as the ATP-induced I(SC)reversedly. Competitive RT-PCR demonstrated that the expression of both ENaC gamma subunits and CaCC was enhanced in Matrigel-treated cultures. However, the observed reduction in the ATP-induced or CaCC-mediated I(SC)could not be explained by the CaCC expression pattern. These data suggest that inhibition of CaCC function is due to enhanced ENaC expression. Therefore, in addition to interacting with CFTR, ENaC also appears to interact with CaCC in the mouse endometrial epithelium. Physiologically the present findings indicate that enhanced expression of ENaC leads to suppression of other Cl(-)channels, such as CFTR and CaCC, thereby preconditioning the endometrium in favour of overall salt and water absorption as observed during embryo implantation.

Adenosine Triphosphate↗

HGF-induced tubulogenesis and branching of epithelial cells is modulated by extracellular matrix and TGF-beta.

Beginning with the observation that hepatocyte growth factor (HGF) induces the formation of branching tubular structures in Madin-Darby canine kidney (MDCK) cells cultured in Type I collagen gels but not in basement membrane Matrigel, we examined the individual components within this complex basement membrane extract to determine the effect of these proteins on the morphogenetic changes mediated by HGF. After extraction of several growth factors from Matrigel, HGF was still unable to induce process formation, an early event in tubulogenesis, indicating that one or more of the remaining extracellular matrix (ECM) proteins or growth factors were exerting the inhibitory effect. By individually adding back these components to MDCK cells grown in Type I collagen gels in the presence of HGF, we were able to establish that: (1) certain ECM proteins, such as laminin, entactin, and fibronectin, actually facilitated the formation of branching tubular structures and increased their complexity; (2) other ECM proteins, such as Type IV collagen, heparan sulfate proteoglycan, and vitronectin, caused marked inhibition of HGF-induced morphogenesis; and (3) not only did transforming growth factor-beta (TGF-beta) inhibit the formation of tubular structures, but those which did form exhibited little branching, thereby suggesting that TGF-beta modulates tubulogenesis as well as branching. These results suggest that a tubulogenic morphogen such as HGF and a tubulogenesis-inhibitory morphogen such as TGF-beta can, in the context of the dynamic matrix known to exist during epithelial tissue development, modulate the degree of tubule (or ductal) formation, the length of these tubules, and the extent of their arborization. The relevance of these findings to tubulogenesis and branching during kidney development is discussed.

Animals↗

Cell-cell interactions affect the accumulation of a cytokeratin-like protein during lens fiber development.

Extracellular matrix proteins were presented in culture to postmitotic, epithelial precursors of chick lens fiber cells as rigid, planar surfaces or malleable gels. Their ability to maintain and promote differentiated characteristics was judged by tritiated thymidine incorporation, immunologic detection of a cytokeratin-like protein (CP49) which accumulates during lens fiber development, and the formation of multicellular aggregates known as lentoids. Regardless of their composition, planar substrates stimulated the reentry into the cell cycle by promoting cell spreading. Laminin- and type IV collagen-coated surfaces facilitated monolayer growth and no appreciable accumulation of CP49. Thin films of Matrigel, which initially stimulated cell division, eventually promoted the formation of extensive lentoids, multicellular aggregates exhibiting many morphologic and biochemical properties of lens fibers. Malleable gels of Matrigel, however, inhibited cell division and immediately allowed the cells to begin lentoid formation. Culture conditions which favored lentoid formation also showed greatly enhanced levels of CP49 accumulation. In addition, lentoids were also shown to accumulate an integral membrane protein (MIP26) which is present in communicating junctions between neighboring fiber cells. These studies indicate that increased cell associations within forming lentoids may influence the progression of lens fiber terminal differentiation in vitro.

Animals↗

Reciprocal interactions between human ovarian surface epithelial cells and adjacent extracellular matrix.

The human ovarian surface epithelium (OSE), or ovarian mesothelium, is functionally complex as seen by its capacity to proliferate, migrate, and contribute to ovulation and ovulatory repair in response to cyclic hormonal and environmental changes. We wished to determine whether this phenotypic versatility is reflected in cell-extracellular matrix interactions in primary and low-passage culture. Comparisons of cultures maintained on different substrata revealed that these cells form cohesive monolayers on plastic, while fibrin clots enhance cell dispersion, and thus may provide a migratory cue. The cells invaded Matrigel as multicellular aggregates, while collagen gels mediated a morphologic epithelial-mesenchymal conversion. On plastic, the cells produced extracellular matrix components characteristic of epithelial basement membrane (laminin and collagen type IV), as well as stroma (collagen types I and III). In addition, ovarian surface epithelial cells secreted serine proteases and matrix metalloproteinases. The levels of chymotrypsin- and elastase-like proteases were dictated by the substratum: low levels were secreted by cells grown on plastic, intermediate levels on collagen gels and fibrin clots, and most protease was produced on Matrigel. The rate of cell proliferation varied with the substrata and was inversely related to protease secretion. Integrin expression was greatest on plastic and least on collagen gels where integrins were downregulated with time. alpha 6/beta 4 was absent from all cells while varying levels of alpha 2, alpha 3, alpha 5, beta 1, and vitronectin receptor were detected depending on the culture substratum employed. In low-passage cultures of human ovarian surface epithelial cells, then, cell shape, growth, protease production, and integrin expression are modulated by the extracellular matrix. The cells, in turn, alter extracellular matrix by synthesis, lysis, and physical remodeling, and express both stromal and epithelial characteristics. The broad repertoire of these functions may be related to their mesodermal origin, and may reflect the expression of a dual, epithelio-mesenchymal phenotype by relatively immature, uncommitted cells. The results demonstrate the great complexity and versatility of these interactions which render OSE cells capable of participating in numerous physiological and pathological processes.

Adult↗

The alpha 3 beta 1 integrin is involved in melanoma cell migration and invasion.

The VLA3 (alpha 3 beta 1) integrin receptor recognizes several ligands; however, the function of this integrin is still debated. Expression of VLA3 appears to be increased in malignant melanoma and correlates with the degree of dermal invasiveness. Here we have studied the role the alpha 3 integrin subunit in malignant melanoma cell migration and invasion into extracellular matrices. The 2/14 clone of the Me665/2 human melanoma cell line, which expresses high levels of VLA integrins, was highly migratory and invasive, while the low integrin expressing 2/56 clone showed limited migration and was not invasive. Antibodies to the beta 1 subunit inhibited adhesion, migration, and invasion of two different malignant melanoma cell lines, the 2/14 clone and A2058 cells, indicating a crucial role for VLA integrins in these phenomena. While anti-alpha 6 antibodies inhibited adhesion to laminin and anti-alpha 5 antibodies inhibited adhesion to fibronectin, antibodies to the alpha 3 subunit did not inhibit adhesion of these cells to laminin, fibronectin, or collagen i.v. In contrast, the P1B5 anti-alpha 3 antibodies were good inhibitors of the migration of these cells toward laminin, fibronectin, and collagen IV and also blocked invasion of these cells through a reconstituted basement membrane matrix (Matrigel). Another anti-alpha 3 antibody, F4, did not effect migration, while both the P1B5 and F4 antibodies induced cellular aggregation on Matrigel. Our data suggest a specific role for alpha 3 beta 1 in the migration and invasion of melanoma cells.

Antibodies, Monoclonal↗

Functional characterization of the spontaneously transformed human umbilical vein endothelial cell line ECV304: use in an in vitro model of angiogenesis.

To gain insight into the role of the endothelial cell during the pathophysiology of the angiogenic response, investigators have isolated micro- and macrovascular endothelial cells from a wide range of both animal and human vessels, including the umbilical vein. Human umbilical vein endothelial cells (HUVECs) isolated from umbilical cords remain a readily available and popular source of endothelial cell. However, the isolation and culture of these cells have several disadvantages, including the risk of infection, exogenous growth factor requirement, and low proliferative capacity. The heterogeneity of endothelial cells from different vascular beds as well as the heterogeneity between HUVEC isolates from different cords can make the critical interpretation of results difficult. ECV304 is a unique spontaneously transformed human umbilical vein endothelial cell line. In this report, the novel use of ECV304 cells as an alternative to HUVECs in an in vitro model of angiogenesis using the reconstituted basement membrane extract (Matrigel) was investigated. ECV304 cells were characterized immunohistochemically and their angiogenic behavior on Matrigel was analyzed functionally by phase-contrast, electron, and time-lapse video microscopy. ECV304 cells had several practical advantages over HUVEC culture and in contrast to HUVECs, ECV304 cells exhibited an enhanced and highly reproducible capacity for in vitro angiogenesis. However, several differentiated functions were lost or reduced in the ECV304 cell line which also exhibited anomalous cytokeratin expression. ECV304 cells may provide novel insights into the mechanisms governing angiogenesis under both normal physiological and pathological conditions.

Animals↗

Influence of extracellular matrix macromolecules on normal human keratinocyte phenotype and parathyroid hormone-related protein secretion and expression in vitro.

Parathyroid hormone-related protein (PTHrP) is produced by a wide range of neoplastic and normal cells, including keratinocytes where it may be involved in the regulation of cellular growth and differentiation. There is evidence that the nature of the extracellular matrix (ECM) influences gene expression and cell phenotype. The objective of this study was to investigate the phenotype of normal human keratinocytes grown on different types of ECM (basement membrane components or collagen type I), as well as the expression and secretion of PTHrP. Normal keratinocytes grown on basement membrane extract (Matrigel) actively reorganized the matrix and formed networks of cells with traction of the matrix. This was associated with linear arrays of intracellular microtubules and formation of prominent actin stress fibers and was suppressed by treatment with colchicine or cytochalasin B, confirming the role of the cytoskeleton in this process. In addition, growth on Matrigel was associated with increased PTHrP nuclear translocation, secretion, and mRNA expression compared to growth on collagen where keratinocytes exhibited decreased proliferation and increased differentiation. PTHrP, as a paracrine keratinocyte factor, did not appear to mediate the morphologic changes, since they were not altered by treatment with neutralizing anti-PTHrP antibodies. It was concluded that different types of ECM influenced the morphologic, functional, and proliferative characteristics of keratinocytes, as well as the level of PTHrP expression and secretion in vitro.

Antibodies↗

Nerve guides seeded with autologous schwann cells improve nerve regeneration.

This study evaluates the ability of Schwann cells (SCs) transplanted into a nerve guide to improve regeneration and reinnervation after sciatic nerve resection and repair, leaving a 6-mm gap, in the mouse. SCs were isolated from predegenerated adult sciatic nerves and expanded in culture using a chemically defined medium. Syngeneic, isogeneic, and autologous SCs were suspended in Matrigel and seeded in resorbable, permeable poly(l-lactide-co-epsilon-caprolactone) guides at 150,000 cells/tube. Guides containing SCs were compared to guides filled with Matrigel alone and with peroneal nerve autografts. Functional reinnervation was assessed by noninvasive methods to determine recovery of sweating, nociceptive, sensory, and motor functions in the hindpaw during 4 months postoperation. Morphological analysis of the regenerated nerves was performed at the end of follow-up. The group with an autograft achieved faster and higher levels of reinnervation and higher number of regenerated myelinated fibers than groups repaired by tubulization. The immunogenicity of transplanted SCs influenced the outcome of nerve regeneration. Transplants of autologous SCs resulted in slightly lower levels of reinnervation than autografts, but higher recovery and number of regenerated fibers reaching the distal nerve than transplants of isologous and syngeneic SCs, although most of the differences were not statistically significant. Syngeneic SCs did not improve regeneration with respect to acellular guides. Prelabeled transplanted SCs were found to survive into the guide 1-3 months after implantation, to a larger number when they were autologous than syngeneic. Cellular prostheses composed of a resorbable guide seeded with autologous SCs appear as an alternative for repairing long gaps in injured nerves, approaching the success of autografts.

Action Potentials↗

In vitro culture of the mosquito stages of Plasmodium falciparum.

The sporogonic cycle of Plasmodium falciparum was obtained in vitro. Mature gametocytes, from blood-stage cultures, produced gametes that underwent fertilization at elevated pH and ambient temperatures. Wheat germ agglutinin stimulated transformation of zygotes into retorts and ookinetes. Twenty-four hours thereafter, 18-49% mature ookinetes and 10-20% intermediate retort forms were counted. Cultures were seeded onto a basement membrane-like gel (Matrigel) in coculture with Drosophila melanogaster cells. Both ookinetes and retorts attached to Matrigel and transformed into oocysts. Mature oocysts and sporozoites expressed circumsporozoite protein. The entire life cycle of Plasmodium falciparum, the most important malaria pathogen of humans, can now be studied in vitro.

Animals↗

Role of integrins in invasion of endometrial cancer cell lines.

OBJECTIVE: The objective of this study was to determine whether there is a link between integrins and components of the plasminogen system, regarding tumor cell invasion to the artificial extracellular matrix. METHODS: Immunocytochemistry was performed with antibodies directed against integrins alpha2beta1, alpha4beta1, alpha5beta1, alpha6beta1, and alpha(nu)beta3 Cell adhesion was studied by cell attachment to matrix proteins. Integrin-mediated migration of cells into the artificial matrix was studied in an invasion assay. Last, immunoreactivity of the components of the plasminogen system was estimated by ELISA. RESULTS: HEC-1A, Ishikawa, and AN3CA cell lines express the alpha 4 beta 1, alpha 5 beta 1, and alpha 6 beta 1 integrins. Adhesion of cells to fibronectin and laminin was inhibited by monoclonal antibodies directed against appropriate integrin subunits. Migration into the matrigel was partially blocked with mAbs to alpha4beta1 as well as alpha5beta1, alpha6beta1 integrins and their combination. No differences in either uPA or PAI-1 immunoreactivity were found after addition of the mAbs. CONCLUSION: Alpha4beta1, alpha5beta1, and alpha6beta1 heterodimers mediate adhesion as well as migration into the artificial matrix matrigel of endometrial tumor cell lines. A cooperative signaling between these integrins and uPA or its inhibitor in modulation of in vitro cell invasion is rather unprobable.

Antibodies, Monoclonal↗

Comparison of techniques for harvesting enterocytes for transplantation.

Selective enterocyte transplantation is a potential alternative to small intestinal transplantation for treatment of the short bowel syndrome. Our aim was to compare chelation and enzymatic methods of isolating enterocytes with respect to initial cell yield and characteristics and in vitro growth. Enterocytes were harvested from adjacent ileal segments in 35 rabbits using chelation with EDTA and warm trypsinization. Determinations were made of initial viability by trypan blue exclusion, cell yield, and proportion of intact crypts. Cells (5 x 10(6)) were seeded in growth media into culture vessels. Cell attachment was estimated by measuring cells liberated by Dispase at 24 hr. In vitro growth was assessed at 14 and 28 days. Although total cell yield (15.0 +/- 9.9 vs 12.5 +/- 8.3 x 10(6) cells/cm) and intact crypts were similar, the trypsin technique resulted in cells with higher initial viability (86 +/- 7 vs 71 +/- 18%, P < 0.05). Cell attachment (7 +/- 8 vs 8 +/- 4%) and enterocyte disaccharidase activity were similar using both techniques. While the number of epithelial cell growth foci was not significantly different at 14 days, there was significantly greater surface coverage on both plain (44 +/- 20% vs 1 +/- 0%, P < 0.05) and Matrigel-coated (80 +/- 14 vs 16 +/- 25%, P < .05) vessels at 28 days with trypsin-isolated cells. Trypsinization resulted in a cell population which had a higher percentage of viable cells but a similar proportion of intact crypts and differentiated cells compared to those resulting from the chelation technique. Trypsin-liberated cells had greater capacity for in vitro growth particularly on Matrigel-coated surfaces.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Matrix metalloproteinase inhibition suppresses MMP-2 activity and activation of PANC-1 cells in vitro.

BACKGROUND: We have shown previously that the metalloproteinase inhibitor, BB-94, prolongs survival and attenuates MMP-2 activity in a murine model of pancreatic cancer. The purpose of this study was to determine the effect of BB-94 on the activity and activation of MMP-2 by PANC-1 cells in vitro. MATERIALS AND METHODS: The poorly differentiated pancreatic cancer cell line PANC-1 was stimulated in vitro with the phorbol ester PMA (20 nM) and grown in the presence of increasing doses of BB-94 (0, 40, 200, and 400 ng/ml) for 24 h. Activation of MMP-2 was determined by gel zymography. In a separate experiment detailing the effects of BB-94 on MMP-2 activity, PANC cells were stimulated for 24 h with PMA and run out on four separate zymograms, each incubated in the previously noted concentrations of BB-94. Using densitometry, band intensity on all gels was determined and compared for each concentration of BB-94. The Matrigel assay was used to determine BB-94's effect on the invasive potential of PANC cells at the previously studied concentrations. The presence of MT-MMP (a putative component of MMP-2 activation) was confirmed using Western blot in each group. RESULTS: BB-94 inhibited the conversion of latent to active MMP-2 in a dose-dependent fashion. BB-94 also inhibited the activity of MMP-2 when run out on gel zymograms incubated with increasing concentrations of BB-94. Decreased activity and activation of MMP-2 by BB-94 were manifested by a significant reduction in the invasive potential of PANC as determined by the Matrigel assay. MT-MMP was universally present in each study group. CONCLUSIONS: The previously described salutary effects of MMP blockade in mice implanted with pancreatic cancer can be explained in vitro by a dose-dependent diminution of MMP-2 activity and activation in PANC cells exposed to BB-94.

Animals↗

In vitro model for developmental progression from vasculogenesis to angiogenesis with a murine endothelial precursor cell line, MFLM-4.

In the embryo, vascular networks are developed through both vasculogenesis, the assembly of vessels from endothelial progenitor cells or hemangioblasts, and angiogenesis, the sprouting of vessels from preexisting capillaries. Cell culture models using endothelial cells (EC) and various extracellular matrix components have been useful in understanding the cellular and molecular factors involved in angiogenesis. However, there are few models of vasculogenesis. Using a murine endothelial precursor cell line, MFLM-4, derived from e14.5 lung mesenchyme, we have developed a culture system that not only recapitulates many of the characteristics of vasculogenesis but also progresses into angiogenesis. By 8 h, MFLM-4 cultured on the basement membrane preparation Matrigel invade the matrix, coalesce, and assemble into large clusters of cells resembling blood islands. During vascular development, blood islands are the focal areas for coalescence of endothelial precursors. For MFLM-4, this phase of in vitro vasculogenic clustering does not require proliferation. If proliferation is not blocked, MFLM-4 progresses into an angiogenic phase with the clusters forming multicell angiogenic sprouts. Through 3 days of culture, lumens form within the clusters, adjacent clusters are connected with tube-like structures, and eventually an extensive network or plexus of clusters connected by capillary-like tubes is formed. MFLM-4 cultured on Matrigel provides an in vitro system for analysis of the multistage, concurrent processes of vasculogenesis and angiogenesis.

Animals↗

In vitro expression of the endothelial phenotype: comparative study of primary isolated cells and cell lines, including the novel cell line HPMEC-ST1.6R.

Endothelial cell lines are commonly used in in vitro studies to avoid problems associated with the use of primary endothelial cells such as the presence of contaminating cells, the difficulty in obtaining larger numbers of cells, as well as the progressive loss of cell viability and expression of endothelial markers in the course of in vitro propagation. We have analyzed the characteristics defining distinctive endothelial phenotypes in the cell lines EA.hy926, ECV304, EVLC2, HAEND, HMEC-1, ISO-HAS-1 and a cell line recently generated in our laboratory, HPMEC-ST1.6R, and have compared these phenotypes with those found in primary human endothelial cells isolated from umbilical vein (HUVEC), lung (HPMEC), and skin (HDMEC). The analysis revealed significant differences in phenotype expression between primary cells and the cell lines. Constitutive expression of von Willebrand factor, CD31, and CD34 and induced expression of cell adhesion molecules, ICAM-1, VCAM-1, and E-selectin and cytokines, IL-6, IL-8, MCP-1, and GM-CSF on stimulation with proinflammatory stimuli, as well as the uptake of DiI-Ac-LDL and the formation of cord-like structures on Matrigel, were typically observed in the primary cells. However, most cell lines exhibited only a few of these endothelial characteristics. Only HPMEC-ST1.6R exhibited the major constitutive and inducible endothelial cell characteristics and showed an angiogenic response on Matrigel similar to that of primary HPMEC. Thus, HPMEC-ST1.6R will be a valuable in vitro model system in which to study pathomechanisms and angiogenesis of the mature microvascular endothelium in vitro.

Antigens, CD34↗